1. Field of the Invention
This invention relates generally to the device configuration and processes for manufacturing inductor coils. More particularly, this invention relates to an improved configuration and process for manufacturing compact and high current inductor coils.
2. Description of the Prior Art
For those of ordinary skill in the art, the configurations and the process of manufacturing a high current inductor coil are still faced with technical challenges that inductor coils manufactured with current technology still do not provide sufficiently compact form factors often required by applications in modern electronic devices. Furthermore, conventional inductor coils are still manufactured with complicated manufacturing processes that involve multiple steps of epoxy bonding and wire welding processes.
Shafer et al. disclose a high current low profile inductor in U.S. Pat. No. 6,204,744, as that shown in FIG. 1. The inductor disclosed by Shafer et al. includes a wire coil having an inner coil end and an outer coil end. A magnetic material completely surrounds the wire coil to form an inductor body. First and second leads connected to the inner coil end and the outer coil end respectively extend through the magnetic material to the exterior of the inductor body. As shown in FIG. 1, the inductor coil 10 is mounted on a circuit board 12. The inductor coil 10 includes an inductor body 14 that has a first lead 16 and a second lead 18 extending outwardly from the coil 10. The leads 16 and 18 are bent and folded under the bottom of the inductor body 14 and are shown soldered to a first pad and a second pad 20, 22 respectively. As shown in FIG. 1B, the inductor 10 is constructed by forming a wire coil 24 from a flat wire having a rectangular cross section. By forming the wire into a helical coil, the coil 24 includes a plurality of turns 30 and also includes an inner end 26 and an outer end 28. A lead frame 32 includes a first lead 16, which has one end 34 welded to the inner end 26 of the coil 24. The lead frame also includes a second lead 18 which has one end 38 welded to the outer end 28 of coil 24. The leads 16 and 18 include free ends 36, 40, which are attached to the lead frame 32. A resist welding process is applied to weld ends 34, 38 to the inner end 26 and the outer end 28 of coil 24.
The inductor coil as shown in FIGS. 1A and 1B by Shafer et al. still have several limitations. Since the wire coil 24 is formed by flat wires that stand on a vertical direction, the height of the flat wire 24 becomes an inherent limitation to the form factor of the inductor coil. Further miniaturization of the inductor coil becomes much more difficult with a vertical standing flat wire as shown in FIG. 1B. The production cost is also increased due to the requirements that the lead frame and the coil must be separately manufactured. The manufacture processes are further complicated since several welding and bonding steps are required to securely attach the welding ends of the flat wire to the welding points of the lead frame. The production yields and time required to manufacture the inductor coil are adversely affected due to the more complicated inductor configurations and multiple bonding and welding manufacturing processes.
Japanese Patent Applications 2003-229311 and 2003-309024 disclose two different coil inductors constructed as a conductor rolled up as an inductor coil. These inductors however have a difficulty that the inductor reliability is often a problem. Additionally, the manufacturing methods are more complicated and the production costs are high. The high production costs are caused by the reasons that the configurations are not convenient for using automated processes. Thus, the inductors as disclosed do not enable a person of ordinary skill to perform effective cost reduction in producing large amounts of inductors as now required in wireless communications.
Therefore, a need still exists in the art of design and manufacture of inductors to provide a novel and improved device configuration and manufacture processes to resolve the difficulties. It is desirable that the improved inductor configuration and manufacturing method can be simplified to achieve lower production costs and high production yield while providing inductors that are more compact with lower profiles such that the inductors can be conveniently integrated into miniaturized electronic devices. It is further desirable the new and improved inductor and manufacture method can improve the production yield with simplified configuration and manufacturing processes.